Dental Practice Education Research UnitAustralian Research Centre for Population Oral Health Adelaide Dental School

The University of Adelaide SOUTH AUSTRALIA 5005 Australia

Tel: +61 8 8313 3291

email: dperu@adelaide.edu.au

FURCATION INVOLVED TEETH

The
progression of periodontal attachment loss to involve the furcation areas
of multi-rooted teeth adds a complex dimension to the diagnosis and treatment
of a patient's periodontal condition. It also alters the prognosis of the
involved teeth, thus affecting the dentist's decisions regarding restorative
options, such as the use of the tooth as an abutment for fixed restorative
work.

ANATOMY

Knowledge of the anatomy
of multi-rooted teeth is essential in order to correctly identify the presence
of furcation involvements.

Maxillary molar teeth:

the mesiobuccal roots are
comparatively wide in the buccopalatal direction, and frequently have marked
concavities

the distobuccal roots are
smaller in dimension, more rounded in outline and less frequently have
distinct concavities

the palatal roots are wider
in the mesiodistal than in the buccopalatal direction

Maxillary prernolar teeth:

most
maxillary first premolars are bifurcated at the middle third of the root
trunk

the canine fossa creates
a deep concavity on the mesial root that merges with the opening of the
furcation

Mandibular molar teeth:

generally have two roots
of similar size and length

* the mesial root is usually
barbell-shaped due to mesial and distal concavities

the distal root has a mesial
concavity and usually has a smaller buccolingual dimension

Diagnosis of furcation
involvement is based upon probing and radiographic findings. Although a
straight periodontal probe may be used, detection of subgingival furcations
is facilitated by the use of specially designed furcation probes (Nabers
No I and No 2 probes). To detect involvement, the tip of the probe is moved
towards the presumed location of the furcation and then curved into the
furcation area. For the mesial surfaces of maxillary molars, this is best
done from a palatal direction, as the mesial furcation is located palatal
to the midpoint of the mesial surface. The distal furcation of maxillary
molars is located more towards the midline, and may be detected from a
buccal or palatal approach. Furcation involvement may be classified into
three degrees, depending upon the extension of destruction in the horizontal
direction.

Degree 1:initial involvement. The furcation opening can be felt upon
probing. The horizontal probing depth is less than one third of the width
of the tooth.

Degree 2: partial
involvement. The horizontal loss of periodontal support exceeds one third
of the width of the tooth, but does not encompass the total width of the
furcation area.

Degree 3:through-and-through
involvement. The probe passes through the entire dimension of the furcation.

Radiographically,
the presence of a furcation involvement. is evident as a radiolucent area
in the vicinity of a furcation. However, due to the superimposition of
roots and bony-structures, there may be little or no radiographic evidence
of Degree I and 2 furcation involvements.

DIFFERENTIAL DIAGNOSES

The progression of periodontitis
to involve the furcation area is not the only cause of bone loss within
a furcation area. The lesion may be endodontic in origin, or may arise
following perforation of the furcation during endodontic treatment or post
preparation. Occasionally, a root fracture will involve the furcation area.
A thorough examination of the tooth is required to form a diagnosis of
the problem.

TREATMENT OPTIONS

There are a number
of options available to manage teeth with furcation involvements. Whatever
the choice of treatment, it is necessary to ensure that healing results
in a morphology in the furcation area that is optimal for oral hygiene
to be performed effectively. In most teeth with Degree I furcation involvement,
this can be achieved by thorough scaling and root-planing. A problem which
arises in root-planing the furcation area is that the entrance of the furcation
is often narrower than the width of the curette blade. The use of older
instruments that have been Finely sharpened to a narrow blade may be useful,
or else there are ranges of curettes with very narrow heads (eg the Gracey
Minis or 'after-five' series of curettes). The use of fine ultrasonic cleaner
tips, for example the Cavitron EWP-IO, EWP-12R and EWP-12L series allows
for access into narrow furcations.

Surgical access is
often required to adequately debride teeth with Degree 2 or 3 furcation
involvements. At the time of surgery, odontoplasty may be performed in
order to widen the furcation opening to the size of an interdental brush.
This may also involve some minor osteoplasty to recontour the bony margins
of the furcation area. The flap may be apically repositioned in order to
allow access for cleaning by the patient. Extensive recontouring of the
roots must be avoided, however, as this can lead to problems of hypersensitivity,
may adversely affect pulp vitality, and it may increase the risk of root
caries. These problems may be minimised by the use of daily fluoride mouthwashes,
and the topical application of fluoride varnishes or desensitising agents.

The development of
guided tissue regeneration techniques has provided an important expansion
to the range of treatment options for teeth with furcation involvement.
This procedure has been most successful in the management, of mandibular
molars with Degree 2 furcation involvements, with more limited success
in maxillary molar teeth.

If teeth with deep
Degree 2 or 3 furcation involvement fail to respond to the above range
of therapies, then root resection is often the next treatment of choice.
It is preferable that the endodontic treatment of the root to be retained
following root resection or tooth hemisection is completed prior to surgery.
If no root can be preserved, then extraction may be the only option. Extraction
may also be performed when the maintenance of the affected tooth is not
essential for a functioning dentition.

PROGNOSIS

The detection of a furcation
involvement can affect the prognosis of the tooth. Therefore, as part of
the initial assessment of every patient, it is essential to judge the location
of the furcations and to prevent them from becoming exposed as a result
of treatment or from disease progression. Studies examining the long term
prognosis of teeth with furcation involvements have shown that maxillary
second molars are most commonly lost, followed by maxillary first premolars.
However, these studies also demonstrate that the vast majority of teeth
with furcation involvements can be successfully treated and maintained
over many years.

This material has
been compiled with the assistance of Dr Louise Brown, Lecturer in Periodontics
at the University of Melbourne.